We have developed an animal model of allergic neuritis (EAN) using Lewis rats wich closely approximates all parameters of Guillian-Barre disease in humans. We have found that the antigen responsible for induction of disease, and the target of immune events, is the P2 protein as a lipid complex with phospholipids. Using this model we are studying the antigenic and disease-inducing sites of the P2 protein, including its amino acid sequence which is nearly completed. We are also studying the immunologic factors involved in induction and suppression of EAN: the P2 protein which suppresses the disease. Extrapolation to G.-B. disease is now a possibility.